Hydrogen is known to have many applications ranging from synthesis of chemicals such as ammonia, petroleum refining in producing high octane gasoline and aviation jet fuel and in removal of sulfur, hydrogenation in various industrial processes, to propellant fuels in combination with oxygen or fluorine for rockets and spacecraft. Pure hydrogen usually takes a form of a colorless, odorless, and tasteless gas composed of diatomic molecules, H2, under ordinary conditions. Alternatively, pure hydrogen may also be stored in the liquid phase under a certain pressure. Pure hydrogen is usually produced by producing the hydrogen gas.
One conventional method of producing the hydrogen gas is by electrolysis of water. This is a simple process in which water (H2O) is decomposed into hydrogen (H2) and oxygen (O2) by electrochemical reactions at the electrodes in an electrolytic cell. The cost of hydrogen generation by electrolysis of water is mainly determined by the cost of energy consumption since the cost of equipment diminishes over many production cycles. The energy consumption in an electrolysis process can be indicated by the operating voltage applied to the electrodes in the electrolytic cell. In ordinary operating conditions, the higher the operating voltage, the larger the energy consumption. A typical operating voltage for electrolysis of water is approximately about 1.4 Volt or higher.
Due to the simplicity of electrolysis process and the equipment, conventional water-based electrolysis systems are widely used in portable or stationary hydrogen generators for small and large scale hydrogen generation. Specifically, hydrogen generation devices can be used as fuel supply for fuel cells that generate electricity by consuming hydrogen.